Details

Updated krb5 packages that fix one security issue are now available forRed Hat Enterprise Linux 3 Extended Life Cycle Support, 5.3 Long Life and5.6 Extended Update Support

The Red Hat Security Response Team has rated this update as having criticalsecurity impact. A Common Vulnerability Scoring System (CVSS) base score,which gives a detailed severity rating, is available from the CVE link inthe References section.

Kerberos is a network authentication system which allows clients andservers to authenticate to each other using symmetric encryption and atrusted third-party, the Key Distribution Center (KDC).

A buffer overflow flaw was found in the MIT krb5 telnet daemon (telnetd).A remote attacker who can access the telnet port of a target machine coulduse this flaw to execute arbitrary code as root. (CVE-2011-4862)

Note that the krb5 telnet daemon is not enabled by default in any versionof Red Hat Enterprise Linux. In addition, the default firewall rules blockremote access to the telnet port. This flaw does not affect the telnetdaemon distributed in the telnet-server package.

For users who have installed the krb5-workstation package, have enabled thetelnet daemon, and have it accessible remotely, this update should beapplied immediately.

All krb5-workstation users should upgrade to these updated packages, which contain a backported patch to correct this issue.

Solution

The krb5 telnet daemon is an xinetd service. You can determine if krb5telnetd is enabled with the commands: